Prosthetic testicles used to adorn the oversized vehicles of those who think very highly of themselves.

They aren't entertaining and they don't make you look cool.
They are contrived and make you look uneducated.

Jeff hung a pair of bumper nuts on his Tacoma.
Jeff's truck only shuttles him to and from work and the grocery store.
He did take it off-road once, and ironically his ground clearance was insufficient to prevent a rock from removing a portion of his oil pan and wrenching the faux balls of his otherwise unused trailer hitch.